Low-viscosity Liquid Research Articles

Numerical and experimental investigation of the effect of interstitial liquid viscosity on the collapse of wet granular columns

The collapse of wet granular columns with high- and low-viscosity interstitial liquid is investigated through experiments and numerical simulations. By incorporating both capillary and viscous force models of interstitial liquid in the Discrete Element Method (DEM), simulations have been conducted and reproduced consistent collapse processes with the experiment. The influence of water content, contact angle, particle diameter, liquid surface tension, and viscosity is explored over a large parameter space using DEM. For wet granular columns with low-viscosity interstitial liquid of water, the final profile of the collapsed column can be predicted by Bond number (Bo), a ratio of particle gravity to capillary force. For wet granular columns where the inertial effect dominates and both capillary and viscous forces are significant, dimensional analysis is employed to characterize the collapse, indicating that the collapsed profile can be predicted by Bo and Galileo number (Ga). Using water and silicone oils with different viscosities as interstitial liquids, simulations show that the collapsed profile depends on Bo with a low capillary number (Ca ∼ 10−3), Bo and Ga when Ca is intermediate (Ca ∼ 10−1). When Ca is high (Ca > 100), the final profile is solely controlled by Bo and a rolling-collapsed regime is observed.

Investigation of keratolytic impact of synthetic bolalipids on skin penetration of a model hydrophilic permeant

Synthetic single-chain bolalipids (SSCBs) are novel excipients in drug delivery, with potential as stabilizers or solubilizers. However, their impact on skin barrier function has not been comprehensively studied. Therefore, two SSCBs (PC-C24-PC and PC-C32-PC) were studied in aqueous systems for their impact on penetration of a model permeant into porcine skin. Concentrations of 0.05 – 5 % w/w were tested; PC-C24-PC formulations were low-viscosity liquids while PC-C32-PC formed viscous dispersions to gels at room temperature. Formulations were compared for their ability to enhance sodium fluorescein penetration (SF, 0.1 % w/w) into skin via tape stripping. Using NIR-densitometry, the effect of SSCB formulations on corneocyte cohesion was evaluated. Data were compared with phospholipid mixture Lipoid S-75, sodium dodecyl sulfate (SDS), and polyethylene glycol 12-hydroxystearate (PEG-HS), and distilled water as negative control. Contrary to the hypothesis, both SSCBs failed to increase SF penetration into the stratum corneum, but rather showed a significant decrease in penetration depth compared to water. Both SSCBs exhibited a keratolytic effect at 5 % w/w, leading to substantial removal of proteins from the skin surface. Consequently, SSCBs may not enhance penetration of hydrophilic drugs into skin, but could be used as keratolytic agents.

Enhanced flexoelectricity of liquid with hydrated ions

Flexoelectricity, denoted as an electromechanical coupling effect from strain gradient introduced polarization, is prevalent in dielectric materials. However, its application in low-viscosity liquids has been limited by the scale of the flexoelectric coefficient. This study explores the flexoelectric coefficient of various hydrated ion solutions through a series of experiments. Additionally, the interplay between ion adsorption and the flexoelectric effect is investigated by using interfacial voltage detection. By introducing hydrated structures into liquids, a significant enlargement of the flexoelectric coefficient up to 2.3 × 10−9 C m−1 is obtained in Fe2(SO4)3 solution by four times than DI water. These findings highlight the remarkable electromechanical properties of liquid materials with hydrated ions and suggest promising avenues for the application of liquid dielectrics in hydrovoltaic technology, ionotronic devices, and energy harvesters.

Experimental Study of the Influence of the Nature of a Surfactant on the Dynamics of Rise of a Group of Monodisperse Bubbles in a Low-Viscosity Liquid

Experimental Study of the Influence of the Nature of a Surfactant on the Dynamics of Rise of a Group of Monodisperse Bubbles in a Low-Viscosity Liquid

Finite element simulation for Si3N4 heating and sintering

The fabrication of large silicon nitride ceramic components is intricate and demands expertise in gas pressure liquid phase sintering (GPS-LPS). The forefront technology of finite element (FEM) thermo-mechanical modeling plays a key role in sizing aerospace components that necessitate high precision and mechanical strength. A comprehensive sintering simulation should encompass not only densification and grain growth models but also consider the heating environment, accounting for gas convection, conduction, and surface-to-surface radiation. Moreover, silicon nitride sintering simulation addresses the intricate behavior, including the swelling phenomenon during the transitions from intermediate to final stage sintering. The challenge of significant slumping in hollow parts, resulting in costly rejection, is a primary concern for industrial companies when dealing with low-viscosity liquid phase sintering. Validation of the model is achieved through the computation of simple cylindrical cases, while a meticulous comparison between simulations and sintering experiments on complex hollow bodies and deflection bars facilitates precise adjustment of the shear viscosity theoretical parameter derived from the Skorohod-Olevsky continuum theory of sintering. The findings from these simple cases guide the simulation of a complex geometry representative of typical aerospace components, determining the ideal sintering configuration to mitigate slumping issues.

Effect of SiO2/MgO ratio on the properties of diopside-based ceramics

Diopside-based ceramics were successfully synthesized by utilizing recovered extracted titanium slag, asbestos tailings, and quartz tailings as raw materials. The objective of this approach is to explore novel sources of raw materials for ceramic production and optimize the utilization of industrial solid waste. The effects of SiO2/MgO mass ratio (S/M) on the properties of the ceramics were studied by investigating the bulk density, bending strength, water absorption and corrosion resistance. The microstructure and crystallization process of the ceramics were analyzed by SEM-EDS and XRD. The results revealed that the increase of S/M is beneficial to the formation of low viscosity liquid phase, the promotion of ion migration and crystallization process, the decrease of sintering temperature, the decrease of water absorption and the increase of bulk density and bending strength of ceramics. In addition, the increase of S/M helps to increase the acid resistance of ceramics. The most optimal parameters (bulk density of 2.97 g·m−3, bending strength of 118.73 MPa, water absorption of 0.29 %, and acid resistance of 98.98 %, respectively) were achieved at the S/M of 2.50 and the sintering temperature of 1175 °C. The increase of S/M ratio also affects the phase reconstruction process. At lower S/M (1.75–2.08), Melilite is transformed into diopside, and at higher S/M (2.50–4.71), Melilite is transformed into diopside and anorthite. The present study aims to optimize the utilization of industrial solid waste (100 %), which not only protects the environment, but also provides a novel approach for resource recovery from such wastes.

Особенности строительного контроля компонентов и конструкции полимерных зон деформационных швов мостовых сооружений

The article considers the construction control peculiarities of components and design of transition polymer zones of bridge structures expansion joints. The authors have examined the transition zones of expansion joints of in-use bridge structures constructed with polymer concrete. The study revealed the lack of regulatory requirements at the national standardization system documents level. The authors confirmed the possibility of binder composition identification at the organisation of construction control of supplied products in accordance with the requirements of design documentation. The authors also confirmed the possibility of determining the products of chemical reaction during curing of polymer concrete in the transition zone of bridge expansion joints. The authors used a low viscosity liquid epoxy resin based on bisphenol with the inclusion of an amine-type hardener to produce a polymer-concrete mixture. When the components are mixed, a composition is obtained that cures and, when bound to mineral aggregate, provides the product with high strength, water resistance, wear resistance and good adhesion to various substrates. The material obtained for bridge constructions is safe for the environment and does not react with various agents. The method of infrared spectroscopy allows identifying the initial substances and reaction products with the probability of coincidence from 70 to 97%.

Development of low-viscosity phosphonium-based ionic liquid electrolytes for lithium-ion batteries: Charge–discharge performance and ionic transport properties

Phosphonium cation-based ionic liquids (phosphonium ILs) have several advantages for electrochemical device applications compared with ammonium cation-based ionic liquids because of their unique features, such as higher ionic conductivity and a larger electrochemical potential window. In this study, we prepared various phosphonium ILs with different substituents (alkyl, alkyl ether, or allyl) on the cation, and bis(fluorosulfonyl)amide (FSA) or bis(trifluoromethanesulfonyl)amide (TFSA) as the anion. This study describes these phosphonium ILs used as electrolytes for lithium-ion batteries and investigates their performance as typical Li/LiCoO2 cells. We demonstrate that discharge capacity increases with increasing lithium-ion conductivity determined by electrochemical impedance and pulsed-field gradient nuclear magnetic resonance. A discharging rate test conducted in constant current (CC) mode also displays good high conductivity phosphonium IL electrolyte performance. Furthermore, the difference in cycle performance between FSA-based and TFSA-based phosphonium IL electrolytes is explained in terms of solid electrolyte interphase formation, similar to the performance of other cation-based ILs.

Upcycling Humins via Esterification Reactions of Hydroxyl Groups: From Functional Powders to PLA Foams and Compatibilized Blends.

The valorization of humins side streams from bio-refineries holds significant economic and sustainability potential. One plausible strategy involves using them as building blocks to create new materials. However, humins pose conceptual challenges in their natural state due to their high viscosity, processing difficulties, and temperature sensitivity. This article presents a synthetic strategy for modifying humins properties to make them thermally stable and processable. Employing a sequence of esterification reactions and varying the reagent steric length, we showcase the selective transformation of humins into thermally-stable fine powders and low-viscosity liquids. We extend this approach by reacting humins with polyesters such as polylactic acids and polycaprolactone. In particular, we detail a one-pot single-step synthesis of micro-phase separated compatibilized blends of polylactic acid and humins capped with the polylactic acid arms. Processed via solution-casting, the obtained materials behave as high-strength thermoplastic elastomers having uniform foam morphologies and material characteristics superior to the pure polylactic acid. By varying the content of D-enantiomers, we demonstrate an additional possibility of manipulating the cellular structures of the foams. Finally, we provide a solution to product circularity by reporting a dissolution recycling method.

Self-Assembled Viscoelastic Surfactant Micelles with pH-Responsive Behavior: A New Fracturing-Displacement Integrated Working Fluid for Unconventional Reservoirs.

The integrated fracturing and oil recovery strategy is a new paradigm for achieving sustainable and cost-effective development of unconventional reservoirs. However, a single type of working fluid cannot simultaneously meet the different needs of fracturing and oil displacement processes. Here, we develop a pH-responsive fracturing-displacement integrated working fluid based on the self-assembled micelles of N,N-dimethyl oleoamine propylamine (DOAPA) and succinic acid (SA). By adjusting the pH of the working fluid, the DOAPA and SA molecules can be switched repeatedly between highly viscoelastic wormlike micelles and aqueous low-viscosity spherical micelles. The zero-shear viscosity of the working fluid enriched the wormlike micelles can reach more than 93,100 mPa·s, showing excellent viscoelasticity and sand-carrying properties. The working fluid is easy to gel-break when it encounters oil, generating a low-viscosity liquid without residue. In addition, the system has strong interfacial activity, which can greatly reduce the oil-water interfacial tension to form emulsions and can achieve reversible demulsification and re-emulsification by adjusting pH. Through the designed and fabricated microfluidic chip, it can be visualized that under the synergistic effect of viscoelasticity and interfacial activity DOAPA/SA can effectively expand the swept volume of tight fractured formations, promote pore wetting reversal and crude oil emulsification, and improve the displacement efficiency. The DOAPA/SA meets the design requirements of the fracturing-displacement integrated working fluids and provides a novel method and idea for constructing the integrated working fluids suitable for fracturing and displacement in unconventional reservoirs.

Effect of B addition on the microstructure and tribological properties of laser cladding FeCoCrNiCu composite coatings

The high-entropy alloy coatings of FeCoCrNiCuBx (x = 0, 0.1, 0.3, 0.5, x values are molar ratios) were prepared on the surface of Q235 steel by laser cladding. The microstructure, microhardness, and surface energy of the FeCoCrNiCuBx coatings were investigated, and the tribological property and wear mechanism of the composite coatings at room temperature (RT) and 600 ℃(HT) were analyzed. The FeCoCrNiCu coating consists of a single FCC-type solid solution. When x = 0.3, 0.5, the composite coatings appear the Cr2B phase. The x = 0.5 (B5) coating has the lowest surface energy (27.45mN/m), which is one of the reasons it has excellent tribological properties. The tribological properties of FeCoCrNiCuBx composite coatings were improved at both RT and HT. The B5 coating has excellent tribology at both RT and HT. At RT, the wear resistance of the B5 coating (wear rate is 8.54 ×10−5 mm3/N∙m, coefficient of friction (COF) is 0.51) was improved by 54.79%, 50.89%, and 12.86% compared with x = 0(HEA), x = 0.1(B1), and x = 0.3(B3), respectively, the COF reduced by 42.69%, 41.39%, 22.73%. At HT the wear resistance of the B5 coating (wear rate is 6.69 ×10−5 mm3/N∙m, COF is 0.24) was increased by 71.53%, 52.91%, and 49.42% compared to HEA, B1, and B3, respectively, the COF reduced by 29.41%, 25.00%, 17.24%. The wear mechanisms of coatings that add B element at RT are abrasive wear and fatigue wear, and at HT are mainly oxidative wear, moderate abrasive wear and fatigue wear.B2O3 melts at HT to form a low-viscosity liquid that forms a lubricating film that isolates the contact surfaces and reduces direct contact and adhesion. This is the main reason for the excellent friction properties of B5 coating at HT.

Behavior of Compound Materials on Superhydrophobic Cylinders: Effects of Droplet’s Size and Interface Angle

Compound droplets can consist of two or more immiscible substances sharing an interface. Among such droplets, the low-viscosity component of Janus droplets can exhibit peculiar bouncing behavior on nonwettable surfaces. There have been recent advances in droplet control technologies, however the impact dynamics of droplets on complex surfaces, and strategies to control their behavior, have not been extensively studied. This study employs the volume of fluid method to analyze the effects of Janus droplet size and the initial interface angle on the dynamics of the two fluidic components in droplets on superhydrophobic cylinders. Janus droplets are composed of low-viscosity (W-) and high-viscosity liquid (G-component). The dynamic characteristics of Janus droplets are investigated as a function of Weber number (<i>We</i>), initial interface angle, the ratio of the droplet’s diameter to the cylinder’s diameter, and viscosity ratio (α). Numerical models provide a regime map of the separation ratio of Janus droplets based on We and α, and the influence of droplet size on asymmetric bouncing is discussed. This study also examines the threshold We at which separation begins after impact, varying with droplet size and α. In addition, the shape evolutions of the droplets are discussed for various initial interface angles to understand the bouncing behavior and separation efficiency. This study is expected to provide valuable strategies for controlling droplet behavior and separation in applications such as liquid purification, rheology, and solidification.

Immiscible invasion of granular suspension by high-viscosity liquid

We investigate the morphology and dynamics of the pattern of immiscible invasion by injecting a high-viscosity liquid into a granular suspension consisting of movable solid grains in a low-viscosity liquid. Laboratory experiments conducted in a Hele–Shaw cell shed light on how the frictional forces of the grains and the viscous forces of the liquids affect the instability of the liquid–liquid interface and the formation of viscous fingers. The frictional force increases with an increase in either the volume fraction or the size of the grains, leading to higher resistance to the invading pattern. Upon changing the grain shape from spherical to irregular, both the frictional force and the rotational energy of the grains increase, resulting in more numerous but narrower fingers. Increasing either the injection rate or the viscosity of the injected liquid increases the viscous pressure within the fingers, promoting the splitting of the pattern. Although the defending liquid always has a lower viscosity than the invading liquid in this study, the former's viscous force becomes non-negligible as the viscosity ratio of the invading liquid to the defending liquid decreases to near unity, which destabilizes the fluid–fluid interface and causes a transition to an asymmetric pattern.

The skating of drops impacting over gas or vapour layers

We report numerical simulations confirming the predictions in Gordillo & Riboux (J. Fluid Mech., vol. 941, 2022, A10), where we elucidated the lubrication mechanism by which a drop of a low-viscosity liquid impacting over a smooth solid substrate skates over a thin gas film that prevents contact with the wall. Moreover, with the purpose of explaining the so-called lift-off mechanism reported in Kolinski et al. (Phys. Rev. Lett., vol. 112, issue 13, 2014, 134501), we extend our previous findings and derive expressions for the time-varying thickness of the gas layer at the region where the distance to the wall is minimum, finding good agreement with the numerical results. In addition, we report that our predictions for the minimum thickness of the gas film separating a falling drop from a wall at room temperature follow closely the experimental values when gas kinetic effects are retained in the analysis, and also report that the analogous equation for the minimum thickness of the vapour layer formed after a drop impacts a superheated wall predicts well the experimental measurements.

Interplay of fluid rheology and micro-patterning toward modulating draining characteristics on an inclined substrate

We investigate a gravity-driven thin film flow of a non-Newtonian liquid over an inclined micro-patterned surface. We demonstrate the effect of micro-patterning on the film draining rate and the velocity profile by varying the relative slit width (Tr) and the length of the periodic irregularities (L). We unveil the interplay of the substrate structure and the fluid rheology by modeling the non-Newtonian thin film using the Carreau model, and the rheology of the film is varied for different values of power index n. Through numerical simulations, we delineate the effects of inertia, viscous, and capillary forces on the physics of thin film flow. We report a significant augmentation of flow velocity for both shear-thinning and shear-thickening fluids as a result of substrate micro-patterning, with the relative slit width playing a dominant role while the length of the periodic irregularities has only a minor influence on drainage characteristics. However, when the sole effect of fluid rheology is considered, flow velocity enhances for pseudoplastic fluid and decreases for dilatant fluid in comparison to Newtonian fluid. We examine the combined effect of rheology and substrate topography, revealing the dominating influence of micro-patterning at high slit-widths, while the fluid rheology has a greater role to play at lower slit-widths. We also demonstrate that the susceptibility of flow physics on varying rheology or topography is greatest for low viscosity liquids. Finally, we mark different regimes where the augmentation of average velocity and surface velocity are individually achieved. Hence, we propose a suitable combination of substrate structure and fluid rheology to engineer a flow characteristic. Based on the suitability for various applications, we provide the key to simultaneously optimizing the fluid rheology and substrate micro-patterning for precise engineering and controlling the draining characteristics of a thin film.

The mechanisms of thermal solidification agent promoting steam diversion in heavy oil reservoirs

At high cycles of steam huff & puff, oil distribution in reservoirs becomes stronger heterogeneity due to steam channeling. Thermal solidification agent can be used to solve this problem. Its solution is a low-viscosity liquid at normal temperature, but it can be solidified above 80 °C. The plugging degree is up to 99% at 250 °C. The sweep efficiency reaches 59.2%, which is 7.3% higher than pure steam injection. In addition, simultaneous injection of viscosity reducer and/or nitrogen foams can further enhance oil recovery. The mechanism of this technology depends on its strong plugging ability, which changes the flowing pattern of steam to effectively mobilize remaining oil. Viscosity reducer and nitrogen foams further expand the sweep range and extends the effective period. Therefore, thermal solidification agent can plug steam channeling paths and adjust steam flowing direction to significantly enhance oil recovery at high cycles of steam huff & puff.

A computational study of cell membrane damage and intracellular delivery in a cross-slot microchannel.

We propose a three-dimensional computational framework to simulate the flow-induced cell membrane damage and the resulting enhanced intracellular mass transport in a cross-slot microchannel. We model the cell as a liquid droplet enclosed by a viscoelastic membrane and solve the cell deformation using a well-tested immersed-boundary lattice-Boltzmann method. The cell membrane damage, which is directly related to the membrane permeability, is considered using continuum damage mechanics. The transport of the diffusive solute into the cell is solved by a lattice-Boltzmann model. After validating the computational framework against several benchmark cases, we consider a cell flowing through a cross-slot microchannel, focusing on the effects of the flow strength, channel fluid viscosity and cell membrane viscosity on the membrane damage and enhanced intracellular transport. Interestingly, we find that under a comparable pressure drop across the device, for cells with low membrane viscosity, the inertial flow regime, which can be achieved by driving a low-viscosity liquid at a high speed, often leads to much larger membrane damage, compared with the high-viscosity low-speed viscous flow regime. However, the enhancement can be significantly reduced or even reversed by an increase of the cell membrane viscosity, which limits cell deformation, particularly in the inertial flow regime. Our computational framework and simulation results may guide the design and optimisation of microfluidic devices, which use cross-slot geometry to disrupt cell membranes to enhance intracellular delivery of solutes.

Dynamics of Low-Viscosity Liquids Interface in an Unevenly Rotating Vertical Layer

Dynamics of Low-Viscosity Liquids Interface in an Unevenly Rotating Vertical Layer

Vapor-liquid equilibrium measurements of ionic liquid [DEME][TFSI] with different hydrofluorocarbon refrigerants R152a, R32, and R143a

To overcome the shortages of traditional working pairs (LiBr/H2O and NH3/H2O) for absorption-refrigeration systems (ARSs), novel working pairs consisting of low global warming potential (GWP) hydrofluorocarbons difluoroethane (R152a) and difluoromethane (R32) plus low-viscosity ionic liquid N,N‑diethyl-2‑methoxy-N-methylethan-1-aminium bis((trifluoromethyl)sulfonyl)amide ([DEME][TFSI]) are studied. Firstly, solubilities of R152a and R32 in [DEME][TFSI] are measured by the isochoric saturation method in the temperature range of 293 K ∼ 343 K and pressure range of 0.14 MPa ∼ 1.664 MPa with the relative expanded uncertainty of 0.03. A high-GWP hydrofluorocarbon 1,1,1-trifluoroethane (R143a) is involved in the experiment for further comparison. The non-random two-liquid model is used to correlate the vapor-liquid equilibrium data with average absolute relative errors of 0.55 % (R152a), 0.58 % (R32), and 0.94 % (R143a), respectively. [DEME][TFSI] shows its low viscosity and good solubility of hydrofluorocarbons by contrast with conventional ionic liquids. A refrigerant solubility rank order in [DEME][TFSI]: R152a > trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) > R32 > 2,3,3,3-tetrafluoro-1-propene (R1234yf) > R143a is obtained from the comparison. This work provides the possibility to apply low-GWP working pairs R152a/[DEME][TFSI] and R32/[DEME][TFSI] in ARSs.

The Mobility of Drops, Pearls, and Marbles

At the scale of drops, water either sticks to inclined solids or moves, yet slowly—without the mobility we expect of a liquid of low viscosity. We first recall that the contact line that bounds a drop is responsible for these special adhesion and enhanced friction properties. Then, we discuss how inducing nonwetting states (pearls and marbles) minimizes the role of this line, restores mobility, and even boosts the liquid when it is viscous.